Process for the dehydration of magnesium chloride



Patented Apr. 11, 1931;

UNITED STATES HAROLD GEORGE LACELL, DECEASED, LATE or FI'NoHnEY, LoNDoN, ENGLAND, BY

LAC LL, EXEGUTRIX, 0F FINCHLEY, LONDON, ENGLAND PATENT orr ce PROCESS FOR. THE DEHYDRATION OIF MAGNESIUM CHLORIDE.

No Drawing. Application filed March 31, 1930, Serial No. 440,637, and in Germany April 5,1929.

on the bath, the latter being held in aclosed This invention is based on the surprising discovery that by adding a relatively small amount of hydrated magnesium chloride to a considerable liquid mass of magnesium chloride which has been substantially completely dehydrated and is suificiently hot, the water of hydration became vaporized and only a small amount of the chloride was converted into magnesium oxide, contrary to what would be expected.

The present invention relates to a process for the dehydration of hydrated magnesium chloride, which consists in the use of the heat capacity of a relatively large mass of magnesium chloride which is practically anhydrous, in order to rapidly raise the temperature of a relatively small amount of magnesium chloride to be dehydrated, thus rapidly vaporizing the water without forming any great quantity of oxide.

Preferably, the mass of magnesium chloride is heated by electricity which disengages heat within the said mass, using alternating current, high frequency induction currents, etc.

It is preferable to add to the magnesium chloride a small amount of potassium chloride, and good results have been obtained with one molecule of potassium chloride for two of magnesium chloride. This lowers the temperature of fusion of the bath, and the dehydration appears to be furthered.

The process may be carried out as follows. An alternating current is sent through a bath of practically anhydrous magnesium chloride and potassium chloride in' the proportion of at least one molecule of potassium chloride for two of magnesium chloride, thus heating the bath to at least 500 C. then adding hydrated magnesium chloride at stated intervals to the hot mass. Each addition of the hydrated material causes a rather violent boiling up, due principally to the disengagement of the water contained in the hydrated magnesium chloride so added. The amount of magnesia produced is always small. The steam thus given off must be at once removed from contact with the bath, for instance by producing a slight suction vessel.

It appears that the important point con sists in the fact of suddenly raisin the temperature of the hydrated magnesium chloride in such manner that the water will be rapidly given off, and thus will not act upon the resulting magnesium chloride. U Q

It is to be noted that the presence of the potassium chloride which is added causes no difficulties in the subsequent use of the magnesium chloride in the electrolytic vats for the production of magnesium.

Further, it is entirely feasible to add the magnesium chloride to bedehydratedfin a ble by suitable additions and an adequate heating.

What is claimed is:

ELIZA i continuous manner, provided ,the'amount of 'chlorlde added is not sufiicient to cause an ex- 1. A process for thedehydration of mag- V 'nesiuin'chloride, which comprises gradually adding, to a relatively large mass of molten anhydrous magnesium chloride, relatively small quantities of hydrated magnesium chloride, thus causing a rapid vaporization. of the water of hydration and thereby preventing the formation of magnesium oxide. '2. Process in conformity to the claim 1,

characterized bythe fact that the temperature of the melted mass is maintained at about 500 (1, and between relatively narrow limits by regulating the heating and byregulating the quantities of the hydrated chloride of magnesium added. I I l 3. Process in conformity to the claim 1, characterized by the fact that the melted mass is heated by heat generated electrically within the body of the mass.

4:. Process in conformity to the claim 1 characterized by the fact of adding potassium chloride to the mass of anhydrous magnesium chloride in order to lower the melting point.

5. Process in conformity to the claim 1 characterized by the fact that the liquid mass is maintained during such process under a partial vacuum to facilitate the vaporizing and removal of the Water of hydration.

6. A process of dehydration of magnesium chloride consisting of maintaining a rel}itively great mass ofanhydrous material rich in magnesium chloride in a molten state, and of adding to that mass relatively smallerv quan;

' 7. A process ofdehydration of magnesium V chloride consisting of maintainingan anhydrousmass relatively rich in magnesium chloride in a molten state, by a heatingthereof without action on the composition offsa'id chloride, and adding to that mass relatively smaller quantities of material rich in hy- 'drated magnesium chloride. LZO

,8. A process of dehydration of magnesium "chloride consisting of maintaining'a relativel'y great mass of material rich inmag'nesiuin chloride in a molten state by heating the said mass to about 500 (3., and adding to that mass relatively smaller amounts of a mass containing hydrated magnesium chloride. n

9. A process of dehydration of magnesium chloride consisting of maintaining a'r'e'latively large anhydrous mass of material which is stable at a high tem erature and which is rich' in magnesium c loride, in a molten state by internally, heating the same to about .500 0., and by adding to this mass relatively smaller quantities of material containing hydrated magnesium chloride. I

'10. A process of dehydrationof magnesium chloride consisting of maintaining a mass of anhydrous material rich in magnsium chloride in a molten state, by'heat geiierated Within said mass of material, and adding tothismass relatively smaller aiipit unts of a materialrichinhydrated magnesium chloride.

p '11. A process of dehydration oif'iiiag'ri} sium chloride which comprises'maiiitaining a relatively great quantity of substantiallyaiihydrous material rich in magneslum chloride, at a'temperature at which such material is molten, and While under a pressure below normal atmospheric, and adding to that mass relatively smaller quantities of a material rich in hydrated magnesium chloride. I V f In testimony whereof I have signed this specification.

ELIZA LACEL Emecutm'w of Harold George, L doell', 'D-

- ceased. 

